Scott,

Interesting find, certainly better than the previous one that did not take any horizontal tail data into account.

I must present one caution when using this calculator.  Even if we assume all calculation are done correctly, this calculator is targeting the radio controlled (RC) community.  The calculator is determining the 'stick-fixed' neutral point.  This means the elevator is assumed to be rigidly held in place via electric servo or some other actuator.  When this is true, the entire horizontal stabilizer area can be used in stability calculations.  In our planes, the elevator is free to float so the effectiveness of the stabilizer is reduced.  When the free elevator is added into the calculations, you end up with the 'stick-free' neutral point.   I mention this only because the simpler 'stick-fixed' calculation produces an overly optimistic result for our application that might get someone in trouble.

 

Chris Zavatson

N91CZ

360std.